The invention relates to filtration of cardiac blood flow between an atrial appendage and its associated atrium. The blood filtration prevents the dispersal of thrombi, which may be formed in the atrial appendage, into the body's blood circulation system. In particular the invention relates to implant filter devices, and apparatus for the percutaneous delivery and implantation of such devices in the heart.
Structural heart disease or other cardiac conditions in a patient can result in atrial fibrillation, which in turn causes blood to pool or stagnate in the patient's atrial appendage. Thrombi (i.e., blood clots) are prone to form in the atrial appendages with stagnant blood. The blood clots may subsequently break off and migrate to the brain leading to stroke, or to other parts of the body causing loss of circulation to the affected organ. The left atrial appendage (LAA), which is anatomically disposed on top of the left atrium, happens to be a particularly likely site for harmful blood clot formation. Thromboembolic events such as strokes are frequently traced to blood clots from the LAA.
The risk of stroke in patients with atrial fibrillation may be reduced by drug therapy, for example, by using blood thinners such as Coumadin. However, not all patients cannot tolerate or handle the blood thinning drugs effectively. Alternative methods for reducing the risk of stroke involve surgery to remove or obliterate the LAA. Other proposed methods include using mechanical devices to occlude the atrial appendage opening and thereby stop blood flow from the atrial appendage into its associated atrium.
Another prophylactic method for avoiding strokes or other thromboembolic events caused by blood clots formed in atrial appendages involves filtering harmful emboli from the blood flowing out of the atrial appendages. Co-pending and co-owned U.S. patent application Ser. No. 09/428,008, U.S. patent application Ser. No. 09/614,091, U.S. patent application Ser. No. 09/642,291, U.S. patent application Ser. No. 09/697,628, U.S. patent application Ser. No. 09/932,512, U.S. patent application Ser. No. 09/960,749, U.S. patent application Ser. No. 10/094,730, U.S. patent application Ser. No. 10/198,261, and U.S. patent application Ser. No. 10/200,565, all of which are hereby incorporated by reference in their entireties herein, describe filtering devices which may be implanted in an atrial appendage to filter the blood flowing out of the atrial appendage. The devices may be delivered percutaneously to the heart through the body's blood vessels using common cardiac catheterization methods. These catheterization procedures often involve first deploying an access system to position an access sheath through a patient's vascular system to the interior locations in the patient's heart. The access sheath provides a passageway through which implant devices are passed from outside the patient's body to interior locations in the heart. Delivery of the devices to the LAA may involve transseptal catheterization procedures, in which access to the left atrium is gained from the right atrium by puncturing the intervening septum. One or more independent delivery systems may be used to deliver the devices through the access sheath.
U.S. patent application Ser. No. 09/932,512, U.S. patent application Ser. No. 10/094,730, and U.S. patent application Ser. No. 10/200,565, disclose expandable implant devices which are small and which can be delivered percutaneously by catheters to the atrial appendages. The effectiveness or success of medical procedures using the implant devices may depend on the proper deployment and retention of the devices in a suitable orientation in the atrial appendages. U.S. patent application Ser. No. 09/960,749 discloses a catheter apparatus having position guides. U.S. patent application Ser. No. 10/198,260 discloses a catheter apparatus having a device tether, which allows a deployed device to be retrieved for repositioning as necessary.
Consideration is now being given to improving implant devices and to improving catheterization apparatus including access and delivery systems for the percutaneous delivery of such devices through geometrically complex vascular paths leading, for example, to the left atrial appendage.